Glendonites – climate-sensitive, beauty, and enigmatic pseudomorphs

Glendonites are spectacular calcite pseudomorphs after metastable
cold-water mineral ikaite (calcium carbonate hexahydrate). Even when
parent mineral of these pseudomorphs was unknown, their occurrences
were used as cold-climate markers, as they always co-occurred with
other cold climate indicators, such as dropstones, cold-water faunas
and cooling events revealed through oxygen stable isotope studies.
However, information about Phanerozoic glendonite occurrences is
mainly scattered through little-known publications in the field of
regional geology, and many different names are used for glendonites in
different countries (anthraconites, stellate concretions, hedgehogs,
pineapples, gennoishi, White Sea hornlets, pseudogaulussite,
fundulite, etc). Their very irregular distribution is space and time
suggesting the influence of addition poorly known factors on
glendonite records. Here I will provide a thorough review of
Phanerozoic glendonite morphology, occurrences, stratigraphic and
geographic ranges as well as significance for palaeoenvironmental
reconstructions.